1. On June 16, 1856, the Republican Party held its first convention in the state of Wisconsin. The convention was held in the city of Madison and had a total of 500 delegates present. This convention was significant as it was held just four years after the formation of the Republican Party in the United States.

2. During the year 1933, the state of Wisconsin witnessed the deadliest tornado outbreak in its history on June 16. Dubbed the "Saxby Gale," the outbreak resulted in a total of 12 tornadoes, which killed about 20 people and caused immense damage to properties in the state.

3. In 1991, the Milwaukee Brewers played a 22-inning game against the Chicago White Sox, which lasted for eight hours and six minutes. The game, which began on June 15 but ended early on June 16, was the longest game in franchise history, and the longest game in the American League since 1984.

4. The Wisconsin Center for Academically Talented Youth (WCATY) held its first summer program on June 16, 1987. The program was designed to provide an enriching academic experience for highly talented students in Wisconsin.

5. In 2018, Governor Scott Walker signed a package of bills that aimed to combat Wisconsin's opioid epidemic on June 16. The bills were meant to improve access to treatment and recovery services for opioid-addicted individuals in the state. The signing of these bills was a significant step towards curbing the opioid crisis in Wisconsin.